DD229995A1 - LIQUID CADMIUM-FREE STABILIZER SYSTEM FOR MOLDING POLYVINYL CHLORIDE - Google Patents

Abstract

The invention relates to a liquid cadmium-free, metal salt-containing stabilizer system for molding compositions of polyvinyl chloride. The aim and object of the invention are to provide a stabilizer system by using special diphosphites, which allows the production of completely yellowing-free, highly transparent PVC molded articles with good thermostabilizing effect. According to the invention, this object is achieved in that, in addition to salts of monocarboxylic acids and / or alkylphenols of metals of the 1st and 2nd or the 2nd group of the Periodic Table of the Elements, except cadmium and optionally further costabilizers, liquid oxyalkylene glycol diphosphites of the general formulaWherein R1, R2, R3, R4alkyl, aryl or alkaryl radicals; x2, 3; Y2-4 are contained in amounts of 10.0 to 40.0 wt .-%.

Description

invention registration

Liquid cadmium-free stabilizer system for molding compounds of polyvinyl chloride

Field of application of the invention;

The invention relates to a liquid cadmium-free. metal salt-containing stabilizer system, which is used for the thermal and light stabilization of homo- and copolymers of vinyl chloride.

This stabilizer system is particularly suitable for PVC molded articles, which have to be completely free of yellowing due to their special purpose and have an excellent transparency or glass clarity with good thermal stability. It is said to be used as a substitute for the cadmium-containing stabilizers often used in predominantly plasticizer-containing processing formulations.

Characteristic of the known technical solutions

Numerous publications relate to the use of metal salt-containing stabilizer combinations for homo- and copolymers of vinyl chloride.

It is known that in the application of metal salt-containing primary stabilizers, such as metal soaps or liquid iietallcarboxylaten certain designated Costabilisat'bren substances must be used to ensure special utility properties. Such costabilizers often have synergistic effects with certain

Attributed to metal salts.

H ^ / 1G q / ^. ο i ^ ν. »υ _ 2 -

In this context, organic phosphites are very important. They are present in virtually all liquid metal salt-containing stabilizer combinations customary today and are regarded as indispensable auxiliaries. The organic phosphites have a decisive influence on certain utility properties and in particular give thermostabilizing effects as well as initial discoloration and transparency-improving effects.

Most commonly, the triaryl, trialkyl, and mixed trialkylaryl phosphites are used in practice. Such compounds should as far as possible eliminate the yellow discoloration which frequently occurs in the processing of PVC molding compounds and also contribute to adequate thermal stability. The problem of yellow discoloration occurs especially with cadmium-free stabilizers.

The usual with organic cadmium stabilizer combinations organic phosphites are usually used in cadmium-free stabilizers. Thus, DS-OS 2 515 376 describes a strontium / zinc combination which contains an organic phosphite in the form of triaryl, trialkyl or a mixed arylalkyl phosphite. However, these phosphites are too low in their effectiveness in cadmium-free systems. US Pat. No. 3,576,651 discloses cadmium-free, nontoxic stabilizer combinations which contain as the phosphite component a specific polymeric diphosphite having molecular weights of 1,000, 30 000 included. Although such phosphites cause a slight improvement in the thermostabilizing effectiveness, but they are unsuitable for liquid stabilizer systems, since due to their polymeric structure incompatibilities and deposits occur. In addition, by using phosphites based on higher molecular weight polyols, the discoloration of the PVC molded articles can not be eliminated. Often, the use of such high molecular weight compounds even worsens the initial color.

Object of the invention

The object of the invention is to remedy the deficiency, the cadmium-free stabilizers particularly with regard to the use values initial color, transparency and thermal stability, or to eliminate as far as possible.

Explanation of the essence of the invention

The object of the invention is to modify liquid cadmium-free stabilizer systems for molding compositions of polyvinyl chloride with regard to the structure of the organic: phosphite component used in such a way that they satisfy the stated objective.

According to the invention, the liquid stabilizer system contains not only salts of monocarboxylic acids and / or alkylphenols of metals of the 1st and 2nd or the 2nd group of the Periodic Table of the Elements, except cadmium, and optionally further customary for the processing of polyvinyl chloride costabilizers, such as epoxidized oils, Phenolic antioxidants or polyols, liquid Oxyalkyienglycoldiphosphite the general formula

R ₁ -O _n

R ₁ , R ₂ , R ₃ , R ₄ = alkyl, aryl or alkaryl

rest, x = 2, 3 7 = 2-4

The amounts of these liquid oxyalkylene glycol diphosphites are from 10.0 to 40.0% by weight, based on the total stabilizer system. Either the entire amount of phosphite can consist of a uniform phosphite of this structure or of combinations of several such phosphites.

The production of the diphosphites described is carried out in a known manner by transesterification reactions of triaryl phosphites.

The Stab.ilisatorsystem invention allows for good thermostabilizing effect the production completely vergil-

ο _ *, _λ ; - 4 -

"non-marking and highly transparent PVC molded articles, which were hitherto only accessible through the use of cadmium-containing stabilizers.

embodiments

Thus, a number of liquid stabilizer systems are prepared by reacting the ingredients listed in Table 1 at a higher temperature. Each of these systems is a clear liquid that has no deposits even after prolonged storage.

Table 1

Stabilizer components (in weight ₀ -%) 1 Stabilizer A B - C D e Potassium 2-ethylhexanoate (5.2% K) 2 - - - 9.5 - Barium 2-ethylhexoate (12.8% Ba) 3 50.5 57.0 - 23.5 50.5 A - - - - - - - 65.0 32.0 - 9.5 18.0 - 5.0 9.5 Strontium isononylphenolate (13.5% "Sr) - - 10.5 - - Calcium 2-ethylbutyrate (5.0% Ca) - 5.0 9.5 '- - Zinc 2-ethylhexoate (20.4% Zn) - - 5.0 - - Zinc isononylphenolate (15.2% Zn) 40.0 20.0 10.0 - - Zinc benzoate (19.9% Zn) - - - 10.0 - Di-tert-butyl-p-cresol - - 10.0 - Oxyalkylene glycol diphosphate 10.0 _ Osyalkylene glycol diphosphite Oxyalkylene glycol diphosphate Oxvalkvlenslvcoldit> HOS

phosphite

Diphenyldecyl phosphite - - - - 40.0 (as a comparative example)

The oxyalkylene glycol diphosphites according to Table 1 have the following structure:

p _ ο _ (CH ₂ -CH ₂ -U) ₃ -P

₁₉ H _o: .0_ / OC _{1 p} H

¹² 25 N _p _ ₀ _ (CHCH ₀ ) p ^ T 2 25

σ, -Η, -0

P - O - (CH ₂ --CH ₂ --CH ₂ --O) ₂ - P

₂ -CH ₂ -CH ₂ -O) ₂

^/ 9 ^Il 19 " ^C 6 ⁿ 4 ⁰ \ _O _ η _ fra _nü _n ^ _ ν ' 6 4" 9 "19

^OC 6 ^H 4 ~ ^C 9 ^il 19

₂₂₄ _ _ _P

100 parts of PVC (KS 65) are thoroughly mixed with 43 parts of Dl-2-ethylhexyl phthalate, 3 parts of epoxidized soybean oil and 2 parts of a stabilizer system described in Table 1. Subsequently, the molding compound is rolled on a laboratory mill at I65 ⁰ C to films of 0.2 mm thickness. The films are further pressed in a press at 180 ⁰ C to 4 now strong plates.

The determination of the thermal stability was carried out in a Warmmeumluftschrank at 180 ⁰ C, the time was determined until the onset of blackening of the film. Initial staining was assessed by the SYNMERO ^R color chart.

The transparency was determined with a spectrophotometer, wherein turbidity phenomena were determined by transmission measurements. It is measured in comparison to the

weakened central ray. In this case, the transmission is 100 %, which corresponds to O % haze.

The results of the tests are shown in Table 2.

briefly sums. Thermostability (min) Initial coloration ρ f C VAT ¹ TT? "D Γ \ ^ - \ Transparency (transmission in%) Table 2 80 2.0 95.0 Stabilizer system 85 1.8 95.5 Example A 65 2.8 93.0 Example B 75 2.5 94.0 Example G 74 6.0 72.0 Example D Example E (= comparison example)

Claims (2)

invention claim 1. Liquid cadmium-free stabilizer system for molding compounds of polyvinyl chloride based on the salts of monocarboxylic acids and / or alkylphenols *! of metals of the 1. and 2. or the 2. Group of the Periodic Table of the Elements, except cadmium, organic phosphites and optionally further costabilizers, characterized in that as organic phosphites liquid Oxyalkylenglycoldiphosph.ite the general formula where R.J, Rp, Ro, R ^ = alkyl, aryl or alkaryl radicals x '= 2, 3
y = 2-4 mean, in amounts of 10.0 to 40.0 wt .-%, based
on the entire stabilizer system.